U.S. Pat. No. 4,480,421, issued Nov. 6, 1984 discloses a flap sealer which responds to a stoppage of a conveyor with glue applied to flaps by shifting the stationary plow and glue nozzles upstream to complete the glue application if necessary and to close the flaps.
According to present practice open ended cartons which are loaded and then closed at their ends with end flaps are manipulated in such a way as to close either the upper end flaps or the lower end flaps initially and then to close the remaining flaps.
According to the prior art, converting a machine adapted to close the carton lower end flaps before closing carton upper end flaps into a machine for folding the upper end flaps before folding the lower end flaps is both expensive and time consuming.